The present invention relates to a bumper construction designed for high impact strength, but further designed for flexibility to provide for optimal energy absorption over a given stroke upon a high force bumper impact, such as a vehicle crash.
Regulations and industry standards for modern vehicle bumpers require that bumpers withstand significant impacts without damage to the bumper. Therefore, bumpers must be strong. However, the bumpers must also be flexible enough to absorb energy during a crash over their full stroke while avoiding unexpected collapse. Further, the bumper must also be lightweight to minimize vehicle mass to provide improved gas mileage and to help meet emission standards. There is tension between these requirements. Bumper beams that are sufficiently flexible to bend in their middle/center sections, may be "too" flexible on their ends (i.e., outside of the mounting brackets) to withstand the high forces generated in corner impacts. Alternatively, bumper beams manufactured to be stiff enough for optimal corner impact (such as those with thicker wall materials or higher stiffness materials) have center sections that may be "too" stiff to properly flex and absorb energy over their full stroke. Also, these "stiffer" bumpers may tend to kink, which results in unexpected collapse and low energy absorption. Further, "stiffer" bumpers tend to be heavier, leading to a greater vehicle mass, lower miles per gallon values, and higher emissions.
Accordingly, a bumper construction is desired solving the aforementioned problems and having the aforementioned advantages.